Re: [PATCH v7 1/3] bus: mhi: host: add mhi_power_down_keep_dev()

Manivannan Sadhasivam
2024-04-01T12:10:49Z

On Tue, Mar 05, 2024 at 10:13:18AM +0800, Baochen Qiang wrote:
> ath11k fails to resume:
>
> ath11k_pci 0000:06:00.0: timeout while waiting for restart complete
>
> This happens because when calling mhi_sync_power_up() the MHI subsystem
> eventually calls device_add() from mhi_create_devices() but the device
> creation is deferred:
>
> mhi mhi0_IPCR: Driver qcom_mhi_qrtr force probe deferral
>
> The reason for deferring device creation is explained in dpm_prepare():
>
> /*
> * It is unsafe if probing of devices will happen during suspend or
> * hibernation and system behavior will be unpredictable in this case.
> * So, let's prohibit device's probing here and defer their probes
> * instead. The normal behavior will be restored in dpm_complete().
> */
>
> Because the device probe is deferred, the qcom_mhi_qrtr_probe() is not
> called and thus MHI channels are not prepared:
>
> So what this means that QRTR is not delivering messages and the QMI connection
> is not working between ath11k and the firmware, resulting a failure in firmware
> initialization.
>
> To fix this add new function mhi_power_down_keep_dev() which doesn't destroy
> the devices for channels during power down. This way we avoid probe defer issue
> and finally can get ath11k hibernation working with the following patches.
>
> Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.30
>
> Signed-off-by: Baochen Qiang <quic_bqiang@quicinc.com>

Applied to mhi-next! Note that this patch is also available in mhi-immutable
branch for ath11k maintainers to pull into their tree.

https://git.kernel.org/pub/scm/linux/kernel/git/mani/mhi.git/log/?h=mhi-immutable

- Mani

> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> Reviewed-by: Jeff Johnson <quic_jjohnson@quicinc.com>
> ---
> drivers/bus/mhi/host/internal.h | 4 +++-
> drivers/bus/mhi/host/pm.c | 42 ++++++++++++++++++++++++++++-----
> include/linux/mhi.h | 18 +++++++++++++-
> 3 files changed, 56 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/bus/mhi/host/internal.h b/drivers/bus/mhi/host/internal.h
> index 5fe49311b8eb..aaad40a07f69 100644
> --- a/drivers/bus/mhi/host/internal.h
> +++ b/drivers/bus/mhi/host/internal.h
> @@ -80,6 +80,7 @@ enum dev_st_transition {
> DEV_ST_TRANSITION_FP,
> DEV_ST_TRANSITION_SYS_ERR,
> DEV_ST_TRANSITION_DISABLE,
> + DEV_ST_TRANSITION_DISABLE_DESTROY_DEVICE,
> DEV_ST_TRANSITION_MAX,
> };
>
> @@ -90,7 +91,8 @@ enum dev_st_transition {
> dev_st_trans(MISSION_MODE, "MISSION MODE") \
> dev_st_trans(FP, "FLASH PROGRAMMER") \
> dev_st_trans(SYS_ERR, "SYS ERROR") \
> - dev_st_trans_end(DISABLE, "DISABLE")
> + dev_st_trans(DISABLE, "DISABLE") \
> + dev_st_trans_end(DISABLE_DESTROY_DEVICE, "DISABLE (DESTROY DEVICE)")
>
> extern const char * const dev_state_tran_str[DEV_ST_TRANSITION_MAX];
> #define TO_DEV_STATE_TRANS_STR(state) (((state) >= DEV_ST_TRANSITION_MAX) ? \
> diff --git a/drivers/bus/mhi/host/pm.c b/drivers/bus/mhi/host/pm.c
> index 8b40d3f01acc..11c0e751f223 100644
> --- a/drivers/bus/mhi/host/pm.c
> +++ b/drivers/bus/mhi/host/pm.c
> @@ -468,7 +468,8 @@ static int mhi_pm_mission_mode_transition(struct mhi_controller *mhi_cntrl)
> }
>
> /* Handle shutdown transitions */
> -static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl)
> +static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl,
> + bool destroy_device)
> {
> enum mhi_pm_state cur_state;
> struct mhi_event *mhi_event;
> @@ -530,8 +531,16 @@ static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl)
> dev_dbg(dev, "Waiting for all pending threads to complete\n");
> wake_up_all(&mhi_cntrl->state_event);
>
> - dev_dbg(dev, "Reset all active channels and remove MHI devices\n");
> - device_for_each_child(&mhi_cntrl->mhi_dev->dev, NULL, mhi_destroy_device);
> + /*
> + * Only destroy the 'struct device' for channels if indicated by the
> + * 'destroy_device' flag. Because, during system suspend or hibernation
> + * state, there is no need to destroy the 'struct device' as the endpoint
> + * device would still be physically attached to the machine.
> + */
> + if (destroy_device) {
> + dev_dbg(dev, "Reset all active channels and remove MHI devices\n");
> + device_for_each_child(&mhi_cntrl->mhi_dev->dev, NULL, mhi_destroy_device);
> + }
>
> mutex_lock(&mhi_cntrl->pm_mutex);
>
> @@ -821,7 +830,10 @@ void mhi_pm_st_worker(struct work_struct *work)
> mhi_pm_sys_error_transition(mhi_cntrl);
> break;
> case DEV_ST_TRANSITION_DISABLE:
> - mhi_pm_disable_transition(mhi_cntrl);
> + mhi_pm_disable_transition(mhi_cntrl, false);
> + break;
> + case DEV_ST_TRANSITION_DISABLE_DESTROY_DEVICE:
> + mhi_pm_disable_transition(mhi_cntrl, true);
> break;
> default:
> break;
> @@ -1175,7 +1187,8 @@ int mhi_async_power_up(struct mhi_controller *mhi_cntrl)
> }
> EXPORT_SYMBOL_GPL(mhi_async_power_up);
>
> -void mhi_power_down(struct mhi_controller *mhi_cntrl, bool graceful)
> +static void __mhi_power_down(struct mhi_controller *mhi_cntrl, bool graceful,
> + bool destroy_device)
> {
> enum mhi_pm_state cur_state, transition_state;
> struct device *dev = &mhi_cntrl->mhi_dev->dev;
> @@ -1211,15 +1224,32 @@ void mhi_power_down(struct mhi_controller *mhi_cntrl, bool graceful)
> write_unlock_irq(&mhi_cntrl->pm_lock);
> mutex_unlock(&mhi_cntrl->pm_mutex);
>
> - mhi_queue_state_transition(mhi_cntrl, DEV_ST_TRANSITION_DISABLE);
> + if (destroy_device)
> + mhi_queue_state_transition(mhi_cntrl,
> + DEV_ST_TRANSITION_DISABLE_DESTROY_DEVICE);
> + else
> + mhi_queue_state_transition(mhi_cntrl,
> + DEV_ST_TRANSITION_DISABLE);
>
> /* Wait for shutdown to complete */
> flush_work(&mhi_cntrl->st_worker);
>
> disable_irq(mhi_cntrl->irq[0]);
> }
> +
> +void mhi_power_down(struct mhi_controller *mhi_cntrl, bool graceful)
> +{
> + __mhi_power_down(mhi_cntrl, graceful, true);
> +}
> EXPORT_SYMBOL_GPL(mhi_power_down);
>
> +void mhi_power_down_keep_dev(struct mhi_controller *mhi_cntrl,
> + bool graceful)
> +{
> + __mhi_power_down(mhi_cntrl, graceful, false);
> +}
> +EXPORT_SYMBOL_GPL(mhi_power_down_keep_dev);
> +
> int mhi_sync_power_up(struct mhi_controller *mhi_cntrl)
> {
> int ret = mhi_async_power_up(mhi_cntrl);
> diff --git a/include/linux/mhi.h b/include/linux/mhi.h
> index 77b8c0a26674..cde01e133a1b 100644
> --- a/include/linux/mhi.h
> +++ b/include/linux/mhi.h
> @@ -630,12 +630,28 @@ int mhi_async_power_up(struct mhi_controller *mhi_cntrl);
> int mhi_sync_power_up(struct mhi_controller *mhi_cntrl);
>
> /**
> - * mhi_power_down - Start MHI power down sequence
> + * mhi_power_down - Power down the MHI device and also destroy the
> + * 'struct device' for the channels associated with it.
> + * See also mhi_power_down_keep_dev() which is a variant
> + * of this API that keeps the 'struct device' for channels
> + * (useful during suspend/hibernation).
> * @mhi_cntrl: MHI controller
> * @graceful: Link is still accessible, so do a graceful shutdown process
> */
> void mhi_power_down(struct mhi_controller *mhi_cntrl, bool graceful);
>
> +/**
> + * mhi_power_down_keep_dev - Power down the MHI device but keep the 'struct
> + * device' for the channels associated with it.
> + * This is a variant of 'mhi_power_down()' and
> + * useful in scenarios such as suspend/hibernation
> + * where destroying of the 'struct device' is not
> + * needed.
> + * @mhi_cntrl: MHI controller
> + * @graceful: Link is still accessible, so do a graceful shutdown process
> + */
> +void mhi_power_down_keep_dev(struct mhi_controller *mhi_cntrl, bool graceful);
> +
> /**
> * mhi_unprepare_after_power_down - Free any allocated memory after power down
> * @mhi_cntrl: MHI controller
> --
> 2.25.1
>

--
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